Most of the existing flight simulators use projectors to create an external field of view. Usually, multiple projectors are combined for creating a wide viewing angle similar to the human vision. A collimated projection system is often used to create depth of fields (DOF). The collimated projection system utilizes the effect of multi-reflect and multi-refract to enhance the depth efficiency of an image. After the image is multi-reflected, the light intensity of the image is weakened. This may result in a light intensity difference between an original image and a reflected image. During an actual flight, pilots may encounter a strong backlighting outside the windows, which affects the vision of the pilots. In addition, the light penetrating through the windows and entering the cockpit may affect the operating of the pilots. Since the collimated projection system is limited by the optical mechanism of the projectors, part of the viewing angles and the light intensity are restricted.